1. Field of the Invention
This invention pertains to connecting devices and more particularly to extrusions from which are made extruded nodes used to connect hollow lineal members, and to joined structures that include such extruded nodes.
2. Description of the Art
There are various structures directed toward increasing the strength of a joint between a connecting device and the members attached to it. For example, the practice of drilling through two items to be connected, then rivet bonding the items, is well known in the art. Yet, creating a joint by this method is both time-consuming and expensive. Similar joining methods include resistance spot welding and adhesive bonding. Many developments in the connecting device art have been directed toward lowering the cost of the devices, and decreasing the time and complexity of the joining process while simultaneously maintaining or increasing the strength characteristics, durability, and reliability of the joining devices and the ultimately formed joint.
Some examples of connecting devices of the prior art include the devices disclosed in U.S. Pat. Nos. 2,742,690; 2,990,203; 3,218,097; 3,791,091; 3,851,601; 4,027,987; 4,261,148; 4,353,661; and 4,385,850. These references are directed toward the use of core members onto which protruding members may be applied. Some of the core members of the prior art are used to connect members which protrude from the core at angles, in instances where the complete product cannot be directly manufactured in a single unit. A common example of a core member is the corner joint of a multipiece window frame structure, or the corner member of wall panels, or a central member of a furniture structure or scaffolding.
An exemplary area where the present invention is particularly applicable is in providing structural frame members for vehicles, such as automobiles, airplanes, railway cars, trucks and the like. For over the past decade there has been a thrust in vehicle manufacturing to reduce the overall weight of the vehicle. In the automotive industry success has been attained not only through downsizing of the automobile, but also through the use of lightweight substitute materials, such as aluminum, in place of heavier materials, such as steel. Prior to 1973 what little aluminum was used in cars was typically employed for nonstructural applications. Today there is a significant increase in the aluminum usage primarily in structural applications, such as frames, bodies, drive trains and the like. Note for example U.S. Pat. No. 4,618,163 which pertains to an automobile chassis that includes extruded light metal rods.
The present invention is particularly, though not exclusively, useful in the manufacture of vehicles, such as automobiles. This invention provides benefits in the area of lightweighting with the use of aluminum extrusions, in structural applications, through the use of unique connecting devices. Connecting devices of light metals, such as aluminum, provide ductility, i.e., the ability to be subjected to substantial deformation without fracturing, in addition to providing light weight. Connecting devices that might be employed in the manufacture of automobiles, though successful, may be further improved or replaced by the devices of the present invention. These prior art devices include certain adhesive bonded applications and certain other devices, including but not limited to cast nodes. Extruded nodes may be welded or mechanically joined to extruded lineal members or other lineal members without the necessity for adhesive bonding. In the manufacture of extruded nodes, there is little or no difficulty in holding close dimensional tolerances; thus subsequent machining of the product to hold dimension is typically not required in extrusions. Also the use of extrusions typically results in high quality welds without porosity problems in applications where extruded nodes are welded to other extruded members, such as aluminum extrusions. Additionally, the yield strength and tensile strength of extruded nodes are typically substantially higher than that of other alternative types of nodes.
Accordingly, improved metallic connecting devices are desired which are ductile, lightweight, thin walled, easily connected and provide adequate strength characteristics.